Answer five questions including three questions from section A and any two from section B.

1. (a)Explain the variations in the electropositivity of the following elements

(i) C, Ge and Sn

(ii) Mg, Al, P and Cl2

(b)State the common oxidation states of chromium and lead.

(c) Discuss the similarities in the chemistry of chromium and lead

Your answer should include.

(i) reactions leading to the formation of complexes.

(ii) Reactions with aqueous sodium hydroxide.

2. (a) Differentiate between order and molecularity of a reaction.

(b)The table below shows some data of a reaction

Experiment no.

Concentration of (mol dm-3)

Concentration of B(mol dm-3)

Tate(mol dm-3 s-1)

I

1.00 x10-2

2.80 x 10-3

2.1

II

5.00 x 10-3

2.80 x 10-3

1.1

III

1.00 x 10-2

5.60 x 10-3

4.3

(i)Determine the order of the reaction with respect to A and B

(ii)Write the rate equation for the reaction.

(iii)Calculate the rate constant for the reaction and give its units

(iv)Calculate the rate of the reaction when the concentrations of A and B are 8.50 x 10-3 mol dm-3 and 3.83 x 10-3 mol dm-3 respectively.

(c) State what would happen to the order of the reaction in (b) if B was in large excess. Explain your answer.

(d) Draw a fully labeled energy diagram for the reaction in (b)

3. Discuss the reaction of

(a) amines with nitrous acid

(b) ethanol with sulphuric acid

(c) methyl benzene with chlorine

Your answer should include:

(i)Suitable examples for the reactions in (a)

(ii)Equations for the reactions in (b)

(iii) Mechanisms for the reactions in (c).

4. A solution containing 20g of a polymer X in 1 l of a solvent exerts an osmotic pressure of 1.4mm Hg at 250C.

(i)Explain what is meant by the term osmosis.

(ii)Calculate the molecular mass of X.

(iii)The molecular formula of the monometer of X is (CH2=CHCN)

Determine the number of monomer units in X.

(iv) Draw the general structural formula of X.

(v) Explain why the freezing point depression method is not suitable for determining the molecular mass of a polymer.

(b) (i) Describe how the molecular mass of a substance can be determined by the freezing point depression method.

(ii) Calculate the freezing point depression of the solvent in (a)

(The freezing point constant of the solvent is 50C per litre)

SECTION B

5. Potassium manganate (VII) is not used as a primary standard in volumetric analysis and has to be standardized.

(a) (i)What is meant by the term primary standard?

(ii)State three characteristics of primary standard

(iii) Explain why potassium manganate (VII) is not used as a primary standard.

(iv)Name one substance other than ethanedioc acid, which can be used as a primary standard for potassium manganate.

(b) Explain why hydrochloric acid is not usually used to acidify solutions of potassium manganate(VII).

(c) Acidified potassium manganate (VII) reacts with ethanedioc acid.

Write

(i)the half equation for the reaction

(ii)the overall equation for the reaction

(d) 20.00cm3 of a 0.01M manganate(VII) ion solution required exactly 16.65cm3 of a solution containing 4.8g l-1 of an oxalate(COO-X+)2.2H2O).

Calculate the atomic mass of X.

6. Write equation to show how each of the following compounds can be synthesized in each case indicate a mechanism for the reaction.

(i) (CH3)2C=CH2 from 2-bromo-2-methylpropane.

(ii)(CH3)2C=N-OH from propanone.

(b)Name the reagent(s) that can be used to differentiate between the compounds in each of the following pairs. In each case state what would be observed if each member of the pairs is treated with the reagent(s)

(c)When 400cm3 of a mixture of ethene and ethyne, measured at room temperature was bubbled into excess ammoniacal silver nitrate solution, 2.4g of a white precipitate was formed.

(i)Write an equation for the reaction which took place and name the white precipitate.

(ii) Calculate the percentage by volume of ethene in the mixture.

7. (a)State two factors which determine the magnitude of electrode potential of a metal.

(b)Draw a well labeled diagram to show how the standard electrode potential of zinc can be determined.

(c) The equation below shows the standard electrode potentials for some half reactions

(d)The ionic radii and the molar ionic conductivities, at infinite dilution at 180C of lithium and ceasium ions are given in the table below.

Li+

Cs+

Ionic radius(nm)

0.06

0.17

Molar ionic conductivity(Ω-1cm2mol-1)

33.5

68.0

Explain why the molar ionic conductivity of lithium ions is lower than that of ceasium ions.

(e)A current of 40.5 A was passed through molten lead(II)bromide for 4 hours and the bromine liberated reacted with 94.0g of hydroxybenzene.

Calculate the number of moles of

(i) bromine liberated.

(ii) hydroxybenzene that reacted

(f)Write an equation for the reaction that took place between bromine and hydroxybenzene in (e) and name the product.

8. Explain each of the following observations.

(a) Thee basics strengths of amino benzene, ammonia dimethylamine are in the order.

(b) Beryllium belongs to groupie in the periodic table and yet its chemistry and that of its compounds resembles that of aluminium

(c) Calcium phosphate is insoluble in water but dissolves in dilute hydrochloric acid

(d) Ethene reacts with bromine to form 1,2-dibromoethane.but when the reaction is carried out in the presence of sodium chloride solution.1-bromo-2-chloroethane is formed